import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.IOException;

public class Main {
	private static String getAvg(String input) {
		String[] spInput = input.split(" ");
		double avg = 0D;
		int dataCount = Integer.parseInt(spInput[0]);

		// O(n)法
		for(int i = 1; i < spInput.length; i++)
			avg += Integer.parseInt(spInput[i]);
		
		// O(n / 2)法
		//
		
		avg /= dataCount;
		
		return Double.toString(avg);
	}
	public static void printAvg(String input) {
		String avgStr = getAvg(input);
//		System.out.println(avgStr);//
		int floatLength = avgStr.length() - avgStr.indexOf('.') - 1;
//		System.out.println(floatLength);//
		
		if(floatLength < 2) {
			avgStr += "0";
		} else {
			if(floatLength != 2) {
				int pos3 = Integer.parseInt(avgStr.substring(avgStr.indexOf('.') + 3, avgStr.indexOf('.') + 4));
				if(pos3 >= 5) {
					double tmp = Double.parseDouble(avgStr);
					avgStr = Double.toString(tmp + 0.01D);
				}
			}
			
			avgStr = avgStr.substring(0, avgStr.indexOf('.') + 3);
		}
		
		System.out.println(avgStr);
	}
	public static void main(String[] args) throws IOException {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		String input;
		
		while((input = br.readLine()) != null) {
			int cases = Integer.parseInt(input);
			for(int c = 0; c < cases; c++) {
				input = br.readLine();
				
				printAvg(input);
			}
		} // end of while <- input
	} // end of method main
} // end of class Main